Git

Go to your project page and it will list your "Development url". This is what you will be pushing to. ''Note: If you have a pre-1.6.2 version of Git, you can't clone the repository if it's empty, you'll have to push to it first.''

How can I specify externals? (a.k.a. embeds/libraries)

I tagged my project, but I don't see a file made!

Relax. The packager only runs on set intervals (approximately every 20 minutes), at which point it packages any new tags that were created since its last run. If you tag your project, give it up to 30 minutes or so (on the outside) to build the zip.

Changes to packager settings won't affect whether the packager detects a tag or not - only whether it actually packages it. If you change your packager settings before a tag is built, the new packager settings will be in effect when it goes to build the tag. There's no need to recommit a tag if you change your packaging settings, unless the tag was already built.

Repository hooks

Apart from the obvious problem of malformed URLs, this can also be caused by a repository that has not been pushed to yet. If you created a new library and are trying to refer to it in an external, check if you pushed any commits to the library's repository.